1. Field of the Invention
This invention relates to novel isocyanate functional polymers which are useful as crosslinking agents for polymers containing active hydrogen functionality, and are also useful as moisture curing polymers.
2. Description of the Prior Art
Isocyanate functional polymers are known in the prior art to be useful as crosslinking agents in combination with active hydrogen containing materials, or by themselves as moisture curing polymers. The commercially available isocyanate crosslinkers, however, frequently contain free monomeric isocyanate molecules which can cause handling problems due to their volatility. This is especially true for polyisocyanates which are prepared as the biuret of monomeric diisocyanates since that reaction often does not proceed to 100% completion and the reaction may be reversible even under routine conditions of storage and handling.
Other prior art methods of preparing isocyanate functional polymers have included the polymerization of blocked isocyanate containing unsaturated monomers such as taught in U.S. Pat. Nos. 3,914,335 and 4,008,247, however, these polymers do not involve free isocyanate.
Although some prior art references, such as West German Patent DE26 18 980 C3, teach the preparation of an isocyanate functional unsaturated monomer by reacting a diisocyanate and an unsaturated monomer having an active hydrogen atom, this prior art fails to teach the polymerization of such monomers to produce isocyanate functional polymers.